Many consumer electronic devices use motion sensors, among other input devices, as operator control inputs for the devices. For example, the devices may include gyroscopes and/or accelerometers, which generate sensor data that the devices may use to determine its orientation in free space. An operator changes the device's orientation in space and, in doing so, intends to enter commands to the device. For example, for tablet computers, many gaming applications allow operators to tilt the tablet computer back and forth as a means to effect changes in game play. Similarly, for game consoles, an operator may manipulate game controllers in free space to affect game play. The devices interpret changes in the motion sensor as operator input changes various elements of game play accordingly.
The outputs of many motion sensors rely on the gravitational pull of the earth on components within the sensor. In many use cases, where the orientation of the gravitational pull is constant throughout use of the device, users may operate the device as they intend. In some use cases, however, shown in FIG. 1, the orientation of gravitational pull can vary during device operation, which can cause a device to register inputs that are different than an operator intends.
FIG. 1 illustrates a use case in which the orientation of gravitational forces varies about an operator during use of a device 100. When an operator is aboard a vehicle such as an airplane or a boat, motion sensors within the device 100 may measure the device's orientation Φ with respect to gravity G. During operation, an operator manipulates the device's orientation θ with respect to his/her body. As the vehicle moves, the vehicle may change the device's and the operator's orientation Φ with respect to gravity but the device's orientation θ with respect to the operator may change differently (or may not change at all). If the device changes game play based on changes in the device's orientation Φ with respect to gravity G, operators may perceive the device's response as an erroneous response.
Accordingly, the inventors perceive a need in the art for a processing system that distinguishes device orientation changes with respect to a user from the device's orientation changes with respect to gravity.